Railway-traffic-controlling apparatus



1,678,683 C. S. SNAVELY RAILWAY TRAFFIC CONTROLLING APPARATUS Filed April 192*! s Sheets-Sheet 1 llllll July 31, 1928,

Q Q NM M Q $1 8% E jih l N fi &

INVENTOR CSSnara/r fiflif A WMWM July 31, 1928.

" C. S. SNAVELY RAILWAY TRAFFIC CONTROLLING APPARATUS filed M 8. 1927 e Sheets-Sheet a 6 Sheets-Sheet 4 C. S. SNAVELY July 31, 1928.

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed April 8, 1927 IIII-IIIIJIIIIILI INVENTORIZ' S .Sna .va 4 a-z-W July 31, 1928.

A C. S. SNAVELY RAILWAY TRAFFIC CONTROLLING APPARATUS Filed pril 1927 s Sheets-Sheet 5 INVENTOR C.

gldrmval L r Q'MM July 31, 1928. 1,678,683

C. S. SNAVELY RAILWAY TRAFFIC CONTROLLING APPARATUS Filed A ril 1927 I 6 Sheets-Sheet e Patented July 31, .1923.

UNITED STATES.

cnannn'cn s. snavnmr, or rrr'rsnunen,

PATENT OFFICE.

PENNSYLVANIA, ASBIGNOB TO THE UNION SWITCH & SIGNAL COMPANY, 01 SWISSVALE, PENNSYLVANIA, CORPORATION OF PENNSYLVANIA.

RAILwAY-TRAPFIC-CONTROLLING APPARATUS.

Application filed April 8, 1927. Serial No. 181,987.

"features thereof in claims.

In the. accompanying drawings, Fig. 1 is a diagiammatic view illustrating one form of railway traific controlling apparatus embodying my invention. Fig. 2 is a view showing in vertical longitudinalsection, a portion of the ap aratus illustrated diagrammatically in ig. "1 and also embodying my invention. Fig. 3 is a detail sectional view along the line III-III of Fig. 2. Fig. 4 is a diagrammatic view showing a. -modified form of a .ortion of the'apparatus illustrated in Fig. 1 and also embodying'my invention. Fig. 5 is a vertical longitudinal sectional view of the master controller H illustrated diagrammatically in Fig. 4 together with the circuit controller Q and the. commutating device S operatedthereby and all embodying my invention. Fig. 6 is a view showing in end elevation the devices .illustratedin ig. 5.- Fig. 7 is a sectional :view-along theline VII- VII of Fig. 5. Fig. 8 is a view showing in vertical longitudinal sectionthe motor T illustrated diagrammaticallyin Fig. 4. Fig. 9 is an end view of the motor s own in Fig. 8 with certain of the parts broken away to show theconstruction. v Fig. 10 is a diagrammatic view showing a modified form of apparatus embodying 'myinvention. Fig. 11 1s a view showing one modification of a part of the apparatus shown in Fig. 10 and also em-.

Q .bodying my invention.

Similar reference 'characters'refer tosimilar parts in each of the several views.

Referring first 'to Fig. 1, the reference characters 1 and 1 designate the track rails of 'a-st retch of railwa trackove'rwhich traflie-normally moves in the direction indi cated bythe arrow. Train controlling cur- The supply of current'to the trackwa is controlled by acoding device designate in general b the reference character A. In

the vform ere shown this coding device comprises a rotatable shaft ,2 operatively connected with a constant speed motor M which receives ener from ahe alternator G. Rigidly plurality o code wheels each designated by the reference character E with a suitable distinguishing exp nent and each of which may be of conduct ng material and may be provided at its periphery with alternately disposed insulating segments 3 and conductmg teeth4. Bearing on the periphery of each of the coding wheels E is a brush 5 which isconnected to one of the fixed con tacts of a circuit controller D which may be controlled in a suitable manner. In actual practicethe bircuit controller D will .usually be operated in accordancewith traffic conditions. One terminal of alternator G is connected directly with rail 1, and the other terminal of the alternator may be connected with rail 1" through any selected one of the codingwheels E depending upon the attache to the shaft 2 area.

osition of the circuit controller D. It folows that the alternating current supplied to the trackway by alternator G is riodic'ally interrupted at a'frequency whlch corresponds to the number of teeth in the coding wheel E which is interposed between'the alternator and the track rails. It will benoted that the several coding wheels E. are rovided with. different numbers of conductmg teeth 4. It follows that the alternating current supplied to the track rails is period-- ically interrupted at different frequencies depending u n which of the code wheels is included m'the trackway circuit. "The devi e A'may be constructed to pro- I have shown only three coding wheels. I

will assume that the shaft 2 operates at twenty revolutions per minute and that wheel I? has four conducting teeth, that wheel E has six conducting teeth and that wheel E has nine teeth. It should be clearly understood that these particular values are not essential but I have discovered that with the values stated there is a minimum of interference with the coded currents by stray energy from conductors which may be adjacent the trackway.

With the apparatus thus far described, when circuit controller D is in the position in which it is illustrated in the drawing, so that contact 67 is closed, the alternating current supplied to the trackway by alternator G, which current I will assume to be of 100 cycles per second, is interrupted at a frequency of 180 cycles per minute. Current supplied to the trackway under such conditions I will hereinafter term the proceed code. When contact 6-8 of circuit controller D is closed the trackway is supplied with 100 cycle current interrupted at are. separately responsive current supplied to a frequency of 120 cycles per minute and this .code I will hereinafter term the caution code. In similar manner when contact 6-9 of circuit controller D is closed the trackway is supplied with 100-cycle current interrupted at a frequency of 80 cycles per minute, which current I will hereinafter term the slow code.

' A train indicated diagrammatically at V is provided with governing means which is selectively responsive to the frequency of the periodic interruptions in the 100 cycle thetrackway. I prefer to accomplish this selective response by taking advantage of the phenomenon of electrical resonance. Under some'conditions it may be undesirable to use apparatus which is electrically tuned directly to the code frequencies of the low order which I have suggested. I therefore provide on the train means for creating alternating currents of frequencies higher than but proportional to the frequencies of the periodic interruptions inthetrackway current The train may then be provided, with tuned circuits which to these higher In the present embodiment of frequencies.

I accomplish these results by my invention,

- providing the train with a receiver comprising two magnetizable cores 11 and 11 located in advance of the fbrward axle 10 and disposed in inductive relation with the two track rails 1 and 1 respectively. Core 11 is provided with a winding 12, and core 11 is provided with a similar winding 12, the two windings 12 and '12 being connected in A 'es in such manner that the-voltages induoed therein by train controlling current .rigidly attached to the housing 34.

the decrease of such current. an impulse of the opposite relative polarity is supplied to the relay. The relay It is responsive to the relative polarity of the current supplied thereto and it follows that when the train controlling current supplied to the trackway is being periodically interrupted, the relay R is operated to swing its armature 15 alternately to the right and left at a frequency which corresponds to the frequency of the interruptions in the trackway current.

Associated with relay R is a motor P which is arranged to operate at a speed which depends upon the frequency at which relay It is operated. In the present embodiment of my invention the motor P comprises two stator windings 17 and 18 which are supplied with current from a battery 16 over contacts controlled by relay It. The motor P also comprises a rotor winding 19 which is constantly supplied with current from battery 16. When relay R is energized in one direction, current from. battery 16 flows over contact 15-45 of relay to winding 17 of motor P, and when relay R is energized in the other direction current flows over its contact 15-45" to winding 18 of motor P. a

Referring now also to Figs. 2 and 3, the motor P comprises a suitable housing 3 1 containing a stator 33 which carries the windings 17 and 18 wound in a manner similar to the usual induction motor. The motor also comprises a rotor 32 carrying When train controlling winding 19, and mounted freely on a shaft 35 which is supported in suitable hearings in the housing 34. The rotor 32 is provided with a yoke 42 which receives one end of a leaf spring 43, the other end of which is The rotor 34 is therefore biased to a definite position. The windings 17, 18 and 19 of the motor P are arranged in such manner that when current is supplied to winding 17 of the stator 33, the rotor 32 is moved in a clockwise direction, as seen from the right in Fig. 2, against the bias exerted by spring 43. When winding 18 is energized, however, the rotor is moved in the opposite direction.

Rigidly attached to the shaft 35 is a ratchet wheel 36 which co-operates with a pawl 37 pivoted on a. post 38 attached to the housing 34. As best shown in Fig. 3, the

ratchet wheel 36 and pawl 37 ermlt rotation of the shaft 35 in 8.0lkW1S9 direction as viewed from the right in Fig. 2'but pre- 6 vent motion of the shaft in the opposite direction. A ratchet wheel 39 similar to wheel 36 is rigidly attached to the shaft 35 and this ratchet wheel co-operates with 'a pawl 40 journalled on a pin 41 in the rotor 42. The

10 pawl '40 and ratchet Wheel 39 permit rotation of the rotor 42 in a counter clockwise direction about the shaft 35 as seen from the right in Fig.2 but these members prevent relative motion of the rotor and the shaft in the opposite direction. When relay R is operating intermittently, the rotor 32 is moved a predetermined distance which is defined by the disposition of the motor windings, each time winding 17 is ener- 2 gized by the closing of contact 15-15 of the relay. I will assume that this motion of the rotor is clockwise as viewed from the right in Fig. 2. During this motion of the rotor the pawl 40 engages the ratchet Wheel 39 and rotates the shaft 35 in a clockwise direction as viewed from the right in F ig. 2. When the relay R next becomes 'ener gized in the opposite direction to close contact 1515", the combined effect, of the energization of winding 18 and the bias exerted by spring 43 returns the rotor to its initial position. During this motion of the rotor the pawl 37 engages the ratchet wheel 36 to' prevent rotation of the shaft and 35 the pawl 40 rides-past one or more teeth of the ratchet wheel 39 without moving the shaft. It is manifest, therefore,'that when relay R is operating intermittently the rotor 42 of the motor P oscillates to and fro and 40 that this oscillation of the rotor advances shaft 35 in one direction by a definite amount for each oscillation-of the rotor. It follows that the shaft 35 of the motor P is rotated in a step-by step fashion at a speed 45 which is directly "proportional to the .fre-] quency of the code which is being supplied to the trackway.

A v rotatable shaft 46 isbperatively connected With the shaft 35 throughsome suitable form of impulse absorbing apparatus.

In the form here shown aspiral spring 44 has one end atta'chedto the shaft 35 and has its other end attached to a drum 45 carried by the shaft 46. The step-by-ste motion of the shaft 35, operating through t e spring.

44 causes substantially uniform rotation of the shaft 46.,"The shaft'46 carries a gear 47 which meshes with a pinion 48 on a spindle 100.. A second gear 49 .is .rigidl attached to the spindle 100 and meshes wit a pinion 50 attachedto' the shaft 51 of an alternator L. Due to the step-up gearing interposed between the shaft 46 andthe shaft 51 of the alternator, the alternator is a5 operated at a considerably higher speed than put terminals connected with a rel}? .nated by .the reference character the 'motor P. The alternator L is constructed in the usual manner and comprises a stator winding 20 whichis constantly supplied with direct current from battery 16 as shown in- Fig. 1.- The alternatorL also comprises a rotor winding 21which delivers alternating current-to the conductors 31 and 31 through the usual slip rings andbrushes. By properly adjusting the proportions of the step-up gearing between the shafts 46 and 51, and-by suitable construction of the.

alternator L, thefrequency of the current delivered to the conductors 31 and'3l may quency of the code which is supplied to the trackway to operate the motor P..- Of course the frequency of the current delivered by the alternator is directly roportional to the speed at which this shaft it follows that the frequency of the current supplied to the conductors 31 and 31 is directly proportional to the frequency of the interruptions in the current supplied to the trackwayi For purposes of explanation-I will assume that when the trackway current is periodically interrupted at the rate of 180 cycles per minute in accordance with the proceed code, the frequency of the current delivered by the alternator is 180 cycles per second, but any other suitable ratio could be chosen for the relation between the code fre q-ucncies and the corresponding frequencies of the output of the alternator L. I Connected in parallel with the conductors 31 and 31' are a plurality of tuned circuits each designated by the reference character is driven and be made considerably higher than the fre- F with an appropriate ex onent and each supplying ener y to a recti er designated by the reference c aracter J with a correspondare so .adjusted and' proportioned that each relay K is energized whenthe current delivered by the alternator L is of the frequency at which the associated circuit F is tuned to resonance but that the relay is de-' energized under all other conditions.

In explaining the operation of the up aratus as .a whole, I will first assume t at contact 6-7 of circuit controller D is closed so that current is supplied to' the trackway in accordance with the proceed code. -U1ider these conditions the relay Bis operated at a .frequency of cyclesper minute. 'The' molbr P therefore drives alternator L atj u o such a speed that the current delivered by the alternator is of 180 cycles per secon Current of this frequency energizes relay K but at this frequency the circuits F and F are detuned sothat relays K and K are de-energized. Current from battery 16 therefore flows over front contact 28-28 of relay K to a lamp 22, which lamp therefore becomes lighted to indicate proceed. Whencontact 68 of circuit controller D is closed to supply current to the trackway in accordance with the caution code the relay R operates at a frequency of 120 cycles per minute and under these conditions the cur rent delivered by alternator L has a frequency of 120 cycles per second. Relay K is therefore energized but relays K and K are open so that current flows from battery relay K back contact 29--29 of relay K and front contact 30---3O of relay K to lamp 24.

It should be pointed out that should the supply of alternating current to the track rails be discontinued, or should alternating current be supplied without interruption to the trackway, or if for any other reason the alternator L should fail to operate,

ence character master controller no current would be supplied to the tuned circuits F and the relays K would all be de-energized. In this case current from battery 16 would flow over back contact28--28" of relay K, back contact 29-29 of relay K and back contact 30-30 lamp 25, thereby lighting this lamp to indicate stop.

Referring now to Fig. 4,1 have here shown a modified form of apparatus for operating the alternator L at different speeds which are proportional to the frequency of operation of relay R. In the modification here shown the contacts of relay R operate a master controller designated by the reference character Hwhich drives a circuit controller Q and operates a commutating device designated in general by, the refer- S. Y This commutating device controls thesupply of'current to a motor T which is operatively connected with thealternator L. The alternator L supplies current to a plurality of tuned circuits in exactly the samemanner as in Fig. 1.

Referring now also to Figs. 5, 6, and 7, the

H comprises a plurality of electromagnets disposed circumferem of relay K to pairs of magnets 59 and 59, 60 and 60 61 and 61, are also connected in series. As shown in Figs. 4, 5 and 6, each of the magnets comprises a core 62 which carries the magnet winding and which is provided at its extremity with two radially extending pole pieces 63 and 64. The armature 66 is in the plane defined by the pole piece-63, and the armature 67 is in the plane defined by the pole piece 64. Furthermore the two armatures, which are rigidly attached to the shaft 65 are so disposed that when onearmature 66 is aligned with the pole piece 63 of one pair of magnets the other armature 67 is also aligned with the pole piece 64 of the same pair of magnets. Due to the Z-shape of the armature, it will be plain that when one pair of magnets is energized, the armatures will be moved to a position in which the air gaps between the pole pieces of this pair of magnets and the armatures have their minimum lengths. For example, re-

ferring to Fig. 4, if magnets 58 and 58 are energized, the armatures will assume the posit-ions. in which they are illustrated in the drawing. If now magnets 61 and 61 become energized the armatures will be rotated in a clockwise direction through an angle of 45 degrees and the armatures will then bear the samerelation to the pole pieces of magnets 61 and 61 as the armatures bear to the pole pieces of magnets 58 and 58 as shown in the drawing.

A circuit controller designated in general by the reference character Q, is operated by the shaft 65, and in the form here shown, this circuit controller comprises a rotatable disk 70 of insulating material rigidly attached to the shaft 65. Thisdisk is-provided with a contact strip which covers portions of the periphery ofthe di k 50 that the edge.

of the disk is provided with two conducting segments 70*" separated by insulating segments 70. Bearing upon the edge of the disk 70 are four brushes 71, 72, 73 and 74, which are sup orted by, but insulated from the frame of t e master controller H. (See Figs. 5 audit) These brushes are. 0 disposed about the periphery of the disk that for any position of the disk 7 Q, two and only two of the brushes bear against the conducting segments 7 0 of the disk. The segments -70 are integral portions'of the same *contact member so that these segments are electrically. together., These seg- Fig. 4 by wire 126.

ments are connected by means which will be explained in detail hereinafter with one terminal G of a suitable source of energy not shown in the drawing. This electrical connection is illustrated diagrammatically in In explaining the operation ofthe master controller, I will first assume that the parts of the apparatus occupy the positions, in which they are illustrated in Fig. 4. Under these conditions, relay R is energized to close contact 15.l5 and the armatures of the master controller are aligned with magnets 58 and 58 as has already been explained. With the parts in these positions,-

brushes 72 and 73 en age a conducting segment 7 0 on the disk 0. Current, therefore flows from terminal B of the energy source,

' through contact 1515 of relay R, magnets 58and 58 brush 73, conducting segment and back to terminal C of the same source. The arm'atures on the shaft 65 are, therefore held in a-position in which they'are aligned with the pole pieces of magnets 58 and 58: When relay R next becomes energized to close contact 15-15", current flows from terminal B, through contact 1515 of relay R, magnets 61 and 61, brush 72, conducting segment 70 and back to terminal C. Magnets 61 and 61 are, therefore energized and the circuit just traced for mag.- nets 58 and 58 -is interrupted so that the armatures 66 and 67 are swung into alignment wit-h magnets 61 and 61, thereby rotating the shaft 65 in a clockwise direction as seen in Fig. 4 through an angle of 45 degrees. This motion of the shaft 65 rotates the disk 70 into a position in which-brushes 71 and 72 engage a conducting segment'70 and brushes 73 and 74 engage an insulated portion of the disk 7 0. When relay R next becomes reversed current flows from terminalB, through contact 15-15, magnets 60 and 60, brush 71, and thence to terminal C, therebymoving the shaft 65 through a further angle of 45 degrees intg'a position in which the armatures 66 and 67 are aligned with magnets 60'and 60 operated intermittently, the joint control of the energization of the magnets of the mas- .ter controller H by the contacts of this relay vanced a distance of 45 degrees for each reversal of the relay, and it follows that the speed of rotation of t e shaft is directly proportional to the fre uency at which the relay It operates and is, therefore directly proportional to the frequency at which'thetrackway current is periodically interrupted.

The shaft 65 also operates a commutating' device designated in general by the referand 84 carried b It will be plain from the foregoingthat when relay R is ives the shaft 65 in---a clockwise ence character S and comprising a commutator proper 68 and two brushes 78 and 84 bearing upon the periphery of this commutator. Referring particularly to Figs. 5 and 7, the commutator. 68 comprises a plurality of insulated contact bars 69 and this commutator is figidl attached to the frame of the master contro ler H. The disk 70 of the circuit controller Q, carries two inward-. ly projecting posts 75 and 81, one of which, 75, is electrically connected with the conducting segments 7 0 of the circuit controller Q. The post 75 carries a brush 77 which bears against the inner surface of a collecting ring 7 9 which is constantly connected with terminal 0 of the energy source. It is by means of this arrangement that the ergy which'supplies current to the magnets of the master controller. The post 75' also carries a brush 78 which bears upon the periphery of the commutator 68. The post 81 is also mounted upon the disk 70 but this conducting segmentsof the circuit control-f ler Q, are connected with the sourceof en-.

be plainthat as the sha t 65 of the master controlleg is rotated due to the intermittent operation of the relay R, the brushes 78 the disk 70 are moved around the perip cry of the fixed commutator 68. But the collector ring 80 is constantly connected with the terminal B of the energy source and collector ring 79 is constantly connected with terminal 0 of the same source. The several bars 69 of the commutato are, therefore successively con-' nected with the respective terminals of the energy source as the shaft 65 of the master controller is rotated. A

The commutating device S controls a motor designated in general b the reference character -T (Fig. 4 and il ustrated in de-.

tail in Figs. 8 an 9., This motor comprises a stator provided with a winding 88 which is constructed in a manner similar 'to the armature winding of the usual direct current motor. This winding is connected at intervals with leads which are connected respectively with a plurality of screws 105 mounted upon a suitable terminal board 106. Each bar 69 of commutator 68 is coning 88 of the motor T a rotating magnetic held, the speed of rotation of which is directly proportional to the speed of rotation of the master controller H.

The motor T also comprises a shaft 89 carrying a field structure 87 provided with a rotor winding 150 to which direct current is constantly supplied from terminals B and O of the energy source through binding posts 94 and 95 which carry brushes 92 and 93, respectively. (See Fig. 8.) Brush 93 engages a slip ring 91, and brush 92 engages a slip ring 101. The two slip rings 91 and 101 are connected with the terminals of the rotor winding 150 in the usual manner. The motor T, therefore operates as an inverted direct current motor, that is, the usual fixed pole structure of the direct current motor is here mounted upon the shaft 89 to rotate in accordance with the rotating field caused by the winding 88 which 'is analogous to the usual armature winding of the direct current motors well known in the art. The shaft of the motor, therefore rotates at a speed which is directly proportional to the speed of rotation of the master controller H, and is, therefore directly proportional to-the frequency of operation of the relay R. I

Attached to the shaft 89 of the motor T is an arm 96 carrying a stud 97 to which is attached one end of a spiral spring 98. The other end of the spring '98 is attached to the gear 47 which drives alternator L as in Fig. 2. The radial position-of the stud 97 with respect to the arm 96 may be adjusted to provide different tensions of the spring 98 to absorb the impulses delivered to the shaft 89 and to deliver a substantially uniform turning torque to the gear 47.

It will be apparent from the foregoing explanation that when the trackway current is periodically interrupted to operate relay R' intermittently, the master controller H operates to rotate shaft 65 at a speed which is.

directly proportional to the frequency of the interruptions of the trackway current. The commutating device S is of course operated at the same speed as the shaft of the master controller, and motor T also operates at a speed which is proportional to thefrequency of the interruptions in to, but may be the trackway current. The fre uency of the output current of alternator is, therefore directly proportional considerably higher than, the code frequency, and the alternator may control governing means which is selectively nsive to the frequency of the current delivered .thereto in'the same manner as in F ig. 1. Fig. 10 illustrates a modified form of apparatus for creating alternating currents of comparatively high frequencies which are proportional to the comparatively low fre quencies at which the trackway current is is proportional th d e secon a2;

of the periodic interruptions in the trackway current. For example, as shown in the drawing, the shaft 110 is operatively 'connected with the rotatable armature 19 of a motor P similar to the motor. P in Fig, 1. It will, therefore be plain that shaft 110 is operated by the motor P at a speed which to the frequency of the periodic interruptions in the trackway current. Rig-idly attached to'the shaft 110 is a. cam 111 provided at its periphery with a com paratively largenumber of swells 112 sep arated by notches 113. Operated by cam 111 is a movable contact lever 114 provided with an. insulating cam follower 115 co-operating with the edge of the cam. The lever 114 cooperates with two fixed contacts 114 and .114 in such manner that as the cam 111rotates and the follower 115 alternately engages the swells 112 and the notches 113 in the cam, the lever 114 is swung .into engagement with contacts 114 and 114 alternately. The contacts 114-=114 and 114' 114{ in parallel are connected in series with the primary 116 of a transformer, X which is supplied with direct current from a suitable source such as battery 16. It follows that when the earn 111' is rotated the current in the primary 116 of transformer X .15, v

the same manner as-in Fig. 1. It follows,.

therefore that periodic interruptions of the trackway current of comparatively low 'frequencies are stepped up to alternating cur-- rents of comparatively high frequencies in of transformer X and that the relays K and K are selectively responsive to In Fig. 11, the contacts 114 -114. and

,114114 are replaced by a variable impedance device designated in general by the reference character W and comprising a these comparatively high frequencies.

ma etizable. core 118 having an air gap in which is located a rotatable member 120 of maghetizable material rigidly attached to the shaft 110 driven b the motor P. v The member'120 is provide with alternate poles 121" and notches 122 so that when the memher 120 rotates, the reluctance of the mag- I netic path thrdughthe core 118' and'the mmher 120 is periodically varied a plurality of times for each complete revolution of the shaft 110. The core 118-is provided with a winding 119 which is connected in series with the primary 116 of transformer X and the battery 16. When the shaft 110'is rotated, the current in the primary 116 of transformer X is periodically varied at a frequency which is higher than, but proportional to, the speed of rotation of the shaft 110. The secondary 117 of transformer X supplies current to the tuned circuits F, F and F in the same manner as in Fig. 10.

It will be plain from the foregoing that with the apparatus shown in Fig. 11 the frequency of the current sup-plied by secondary 17 of transformer X is higher than, but proportional to, the frequency of the periodic interruptions of the trackway current.

In Figs. 10 and 11 the shaft 110 is operated by a motor P which in turn is'controlled by a relay which is operated intermittently at a frequency corresponding to the frequency of the periodic interruptions in the trackway current, but this particular arrangement is not essential, the important feature being that the shaft 110 is rotated at a speed which is proportional to such interruptions.

It willbe apparent, therefore, that my invention provides apparatus by means of which alternating currents of commercial frequencies supplied to the trackway may be periodically interrupted at comparatively rangements of apparatus, for operating the alternator L at s eeds which are low frequencies of the order from 1 to 3 cycles per second and'that these comparatively low frequencies control apparatus on board the train which creates alternating currents of frequencies which are higher than, but proportional to, the frequencies of the periodic mferruptions of the trackway current. In systems embodying my invention, therefore, I combine the advantages which result from the use of low frequencies for the various codes, such as freedom from interference, with the advantages inherent to tunin to comparatively high frequencies for se ection between the frequencies.

In each of the forms of apparatus which I have. disclbsed, the. control of the train carried governing means is eifectedthrou h the medium of a relay R which is interm1ttently operated in accordance with the interruptions in the. trackway current, but this particular arrangement is unnecessary. Furthermore it should be pointed out that although I have illustrated two specific arroportional tothe spec of the inter'ru tions in thetrackwaycurrent, any other suitable arrangement of apparatus may be substituted for the mechanism which I have disclosed. Although Ihave herein shown and described only a few forms of railway traflic' 1. In combination, a source of current,

means for periodically interrupting such current, means responsive to such interruptions for creating an alternating currentthe frequency of which is different from, but proportional to,,the frequency of such interruptions, and means selectively responsive to the frequency of such alternating current.

2. In combination, a source of current, means for periodically interruptingsuch' current at different low frequencies responsive to such. interruptions for creating alternating currents the frequencies of which are higher than, but proportional to, the frequencies of such interruptions, and means selectively responsive to the frequencies of such alternating currents.

3. In combination, a source of current, -means for periodically interrupting such current, a motor device responsive to such interruptions, but not to the current itself, an alternator operatively connected with the motor device, and means receiving alternating current from the alternator and 'selectively responsive to the frequency of the received current. I

4. In combination, a source of alternating current, means for periodically interrupting such current, a. motor responsive to the interruptions lIl said current but not to the current itself,'an alternator operated by the f motor, and governing means controlled by the alternator.

' 5. Railway traffic controlling apparatus comprising means for supplying alternating cies, means responsive to such interruptions ,for creating on a'train alternating-currents the frequencies of which are different from, but proportional" to, the frequencies of such interruptions, and governing means on the train selectively responsive to the of such alternatficurrents. I Y v 7...Railwa-'y t e? controlling-apparatus riodically infrequencies 1 current to the trackway,

2 current to the trackway,

comprising a train carried motor, means located partly in the trackway for operating the motor at different speeds, an alternator operatively connected with the motor, and

5 governing means selectively responsive to the 1 motor, a relay receiving energy from-the alternator, and a tuned circuit interposed between the alternator and the relay.

9. Railway traffic controlling apparatus comprising means for supplying alternating means for periodically interrupting such alternating current at difierent frequencies, a train carried motor receiving energy from the trackway and OP,-

crating at a speed which is proportional to 2 the frequency of such interruptions, an alternator operated by the motor, a plurality of relays receiving energy from the alternator, and a plurality of tuned circuits one interposed between each 10. Railway traffic controlling apparatus comprising a train carried relay, means located partly in the trackway for operating the relay intermittently at different frequencies, an impulse motor, means for operatin'g the motor at aspeed which is proportional to the frequency of operation of the relay, an alternator operated by the motor, and governing means selectively responsive to the frequency of the current de- 40 livered by the alternator.

. 11. In combination, an'impulse motor comprising a rotor biased to an initial position, means for periodically moving the rotor away from its initialposition at different 5 frequencies, a shaft rotated in a single direction at a speed which is proportional to the frequency of oscillation of the rotor, an

alternator operated by the shaft, and a plurality of devices selectivelyresponsive to the plied by relay and the alternator.

frequency of the current supplied by the alternator.

12. In combination, an impulse motor comprising a rotor, means for oscillating the rotor through a small angle at difi'erent frequencies',

in one direction for rotor, an alternator operated by the shaft, and a plurality of relays selectively responsive to the frequency of the current supthe alternator.

13. Railway traflic controlling apparatus comprising a train carried motor, means located partly in the trackway for operating the motor at different speeds, an alternator driven by the motor, a plurality of relays receiving energy from the alternator, and resonant means interposed between each relay and the alternator and each tuned to a different frequency.

14. In combination, a. stretch of railway track supplied with alternating current, means for periodically interrupting such current at different frequencies, a train carried relay responding to the interruptions in such current but not to the current itself, a motor controlled by the relay, an alternator controlled by the motor, a plurality of resonant circuits all connected in parallel with the alternator and each tuned to resonance at a different frequency, and a plurality of relays one receiving energy from each said circuit.

15. Railway traflic controlling apparatus comprising a train carried motor having a fixed winding and a movable winding, means for supplying direct current to one of said located partly in the trackway for supplying riodic current to the other winding where y the movable winding oscillates at the frequency of such periodic current, an

windings, means alternator, means responsive to the oscillations of the movable winding of the motor to drive the alternator in one dimotion, and a tuned circuit from the alternator.

In testimony whereof I afiix my signature.

CLARENCE S. SNAYELY;

a rotatable shaft, means for advancing the shaft a predetermined distance each oscillation of thereceiving energy 

